Hand operated, high pressure fluid pumps are used in many applications, often acting as backup pumps in systems that employ power driven pumps as a source of fluid pressure. An emergency engine starting system for military aircraft is one such application. Some aircraft jet engines are started by a fluid motor connected to and operated by fluid pressure stored in an accumulator. The stored pressure is usually 3000 psi or higher. In normal operation, the accumulator is pressurized by the aircraft engine prior to shutdown thus providing a subsequent source of starting energy.
In some instances, the accumulator will become depressurized as a result of maintenance work on the engine, system failure, etc. If the aircraft is located at a fully equipped aircraft base, auxiliary equipment is usually available to start the engine. However, if the aircraft is located in a more remote area where only limited service equipment is available, apparatus for repressurizing the accumulator in order to start the engine must be provided on the aircraft itself.
In the past, this auxiliary apparatus has been a hand operated fluid pump mounted within the aircraft. In the event the accumulator was depressurized, an operating handle was reciprocated to actuate the hand pump to force fluid into the accumulator. It was found, however, that considerable effort and more importantly, a considerable amount of time was expended in completely charging the accumulator. In an emergency situation, the time necessary to start the engine could be detrimental.
It was also found that in many remote areas served by the aircraft, auxiliary power sources such as pneumatically operated tools were available. Consequently, a means for utilizing these limited power sources to aid in charging the accumulator was desired. A separate, power operable pump was considered, but was precluded due to space limitations on the aircraft. The separate power operable pump could not eliminate the hand operated pump currently mounted on the aircraft because a manually actuated pump must be provided on each aircraft to enable the aircraft to be started in areas devoid of any source of power.